Package g0201_0300.s0208_implement_trie_prefix_tree

Class Trie

  • All Implemented Interfaces:
    
public final class Trie

    208 - Implement Trie (Prefix Tree).

    Medium

    A trie (pronounced as "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker.

    Implement the Trie class:

    • Trie() Initializes the trie object.

    • void insert(String word) Inserts the string word into the trie.

    • boolean search(String word) Returns true if the string word is in the trie (i.e., was inserted before), and false otherwise.

    • boolean startsWith(String prefix) Returns true if there is a previously inserted string word that has the prefix prefix, and false otherwise.

    Example 1:

    Input "Trie", "insert", "search", "search", "startsWith", "insert", "search" [ [], "apple", "apple", "app", "app", "app", "app"]

    Output: null, null, true, false, true, null, true

    Explanation:

    Trie trie = new Trie();

    trie.insert("apple");

    trie.search("apple"); // return True

    trie.search("app"); // return False

    trie.startsWith("app"); // return True

    trie.insert("app");

    trie.search("app"); // return True

    Constraints:

    • 1 <= word.length, prefix.length <= 2000

    • word and prefix consist only of lowercase English letters.

    • At most <code>3 * 10<sup>4</sup></code> calls in total will be made to insert, search, and startsWith.